Over the years, global competitiveness in agricultural grains markets and economic pressures on individual grain producers have driven farmers to utilize seeding equipment that provides the greatest possible economy of purchase, operation and maintenance. Equally, farmers have sought equipment that optimizes the potential for crop yields by providing accurate seeding depth, optimizing seed/soil contact, preserving soil moisture, and minimizing soil disturbance which promotes weed growth.
Seeding machines have been developed that allow the placement of seed in a field with minimum tilling or even no tilling. In addition to developing machines that allow seeding alone, a lot of effort and development has gone into developing machines that allow the placement of fertilizer in the soil at the same time the seeding is being done. These machines allow a field to be seeded and fertilized in a single pass.
The machines that have been developed to both seed and provide fertilizer in a single pass are typically modified air seeders. These modified air seeders typically comprise two or more holding tanks, for holding particulate matter, connected to a wheeled frame assembly. Various means for delivering the particulate materials in separate streams to various sub-assemblies for dispensing of the particulate material are used. These prior art machines have taken two distinct routes in their methods of providing both seed and fertilizer in a single pass. The first route is the use of “double shooting” machines. These machines operate by opening a series of furrows in the soil in the field and placing both seed and fertilizer in each furrow. Typically, these configurations are intended to place the seed and the fertilizer in different locations within essentially the same furrow, or in separate furrows that are not much more than one inch apart. Typical arrangements for these types of “double shooting” include systems with a single opener and separate seed and fertilizer ports (such as those systems disclosed in U.S. Pat. No. 6,640,731 to Rowlett et al., and U.S. Pat. No. 6,332,412 to Swab et al.) and systems with a leading fertilizer coulter or hoe followed by a trailing seed coulter or hoe that places the seed and fertilizer in very nearly the same line (such as the system disclosed in U.S. Pat. No. 5,396,851 to Beaujot, U.S. Pat. No. 5,331,907 to Beaujot and U.S. Pat. No. 6,142,085 to Drever et al.
These types of “double shooting” methods all place the fertilizer in relatively close proximity to the seeds. The use of fertilizer at the time of seeding can be greatly beneficial to the seedling emergence and eventual crop yield. Properly fertilizing at the time of seeding can improve the yield of a crop. However, fertilizer that is placed too near the seed can damage the seed and cause delay and reductions in emergence of the crop and can even cause a reduction in the quality and yield of a crop, particularly with more sensitive seeds, in particular soil types and in dry soil conditions. Even if placing the fertilizer too close to the seed only causes delays in the crop maturing, an early frost before the crop has been harvested can have disastrous consequences to the crop. The openers of these units, while mounted on the same “shank”, are staggered somewhat, in an attempt to provide seed & fertilizer rows that are typically spaced about one inch apart. The drawback of these types of assemblies is that in certain soil & moisture conditions, for example drier clay soils that tend to lump, it is very difficult to achieve separation of seed and fertilizer when the seed and fertilizer rows are in such close proximity. Often, some of the seed falls into the fertilizer furrow.
The second route these prior art machines have taken for dispensing seed and fertilizer in a single pass are through “mid-row banding openers”. These types of machines are also modified air seeder type machines and comprise two types of sub-assemblies attached to the frame: fertilizer assemblies and seed assemblies . This type of system is disclosed in U.S. Pat. No. 6,216,616 to Bourgault. The Bourgault system uses coulter disc type fertilizer assemblies that create furrows mid way between adjacent pairs of furrows opened by coulter disc type seed assemblies. However, this system uses the same type of assemblies for depositing both seed and fertilizer and does not allow independent adjustment of the seed placement openers nor does it allow independent depth control of each seed assembly during operation.